Rational construction of thermally stable single atom catalysts: From atomic structure to practical applications

As a new frontier in catalysis field, single-atom catalysts (SACs) hold unique electronic structure and high atom utilization, which have displayed unprecedented activity and selectivity toward a wide range of catalytic reactions. However, many reported SACs are susceptible to Ostwald ripening process in high temperature environment or long-term catalytic application, which will cause sintering and deactivation. This is due to the weak interaction between the metal atom and supports. The regeneration and recycling of deactivated catalysts will greatly increase the time and economic cost of industrial production. Therefore, it is necessary to develop SACs with excellent thermal stability to meet the industrial demands. Here, we discuss the fundamental comprehension of the stability of thermally stable SACs obtained from different synthesis methods. The influences of the speciation of metal centers and coordination environments on thermal stability are summarized. The importance of using novel in situ and operando characterizations to reveal dynamic structural evolution under synthesis and reaction conditions and to identify active sites of thermally stable SACs is highlighted. The mechanistic understanding of the unique role of thermally stable SACs in thermocatalytic application is also discussed. At last, a brief perspective on the remaining challenges and future directions of thermally stable SACs is presented.